1. Field of the Invention
The present invention generally relates to a laser system, more particularly, to a laser system that has double-sided microlens arrays so as to shaping and homogenizing a laser beam.
2. Description of the Prior Art
Projector normally adopts a laser system, which is able to project colorful images with the features of high resolution, high saturation and wide-color-gamut, so that the colors of a screen may be distinct and vivid and closer to natural things. Due to that of a laser beam projected from a light source being a must to meet with the conditions of the shape of the screen and uniform illumination and a circular beam with the Gaussian Distribution of energy, the laser beam shall be shaped and homogenized in order to alter the figure and the energy distribution thereof when the laser beam is as a light source.
With references to FIG. 1, FIG. 2 and FIG. 3, which illustrate a schematic view of a laser beam shaping and homogenizing device, a schematic view of an energy distribution of an incident beam of FIG. 1 and a schematic view of an energy distribution of an emergent beam of FIG. 1. As shown in the figures, the laser beam shaping and homogenizing device 10 is disposed at the path of the laser beam. The circular incident beam with the Gaussian-distributed energy goes through the laser beam shaping and homogenizing device 10, thus the emergent beam becomes a square and flat-top beam with the average uniformity of energy.
Generally speaking, the laser beam shaping and homogenizing device 10 is constructed by some diffractive optical elements, and a microlens array is one embodiment of such diffractive optical elements. The microlens array is actually disposed on the surface of a laminar base plate with lots of micro lenslets. The dimensions of the micro lenslets comply with the classification of the optical diffractive element, and the micro lenslets are tightly lined up the arrangement of a square array.
While the laser beam goes into the microlensl array, the phenomenon of diffraction is thus happening. Continuously, the diffractive light waves pass through the microlens array, the overlapped light waves are reassembled to form the square and flat-top beam. Further, with the projection distance being longer, the uniformity of the laser beam going through the microlens array is rapidly worse. That is, the energy distribution of near field projection spots of the laser beam being just projected from the microlens array is very uniform; on the contrary, the far field projection spots are changed to a dispersed spot array, which cannot meet with the requirements of the uniformity of a projection device/system. Therefore, some other components for the projection device/system must be added to compensate the uniformity of the laser beam, e.g. vibration components to vibrate a projection display in order to achieve the effect of uniform illumination.
The present invention is thus developed based on the shortcomings of prior arts so as to improve the laser beam shaping and homogenizing device and the laser system.